Begins to document enricher.

enricher/README.md

@@ -1,3 +1,29 @@
 # Enricher Component
 
-TODO README...
+TODO introduction...
+
+## Setup
+
+To set this up you'll need the following:
+
+* A [Redis Stack](https://redis.io/docs/stack/get-started/) database. Get a free cloud hosted database [here](https://redis.com/try-free), or use the redis-stack Docker image ([here](https://hub.docker.com/r/redis/redis-stack)) or use the Docker compose file at the root of this repository.
+* A fully set up and working instance of the receiver component ([read about this here](../receiver/README.md)) which is also connected to the same Redis Stack instance you are using for this component.
+* An API key for the [FlightAware Aero API](https://flightaware.com/commercial/aeroapi/). Note this this is a paid API - you do get some calls without charge but you will need to sign up and provide a payment method.
+
+First, configure the environment by copying `env.example` to `.env`. Edit this file to contain the Redis connection URL for your Redis instance ([Redis URL format](https://www.iana.org/assignments/uri-schemes/prov/redis)). You'll also need to add your FlightAware API key to the `FLIGHTAWARE_API_KEY` field.
+
+Finally, install the dependencies:
+
+```
+npm install
+```
+
+## Running the Enricher
+
+Start the enricher component like this:
+
+```
+npm start
+```
+
+TODO what happens...